In many non-invasive or minimally invasive surgical and treatment procedures, navigating a medical device within a patient's body can be very challenging. Navigation systems are frequently used to help the user identify the location of the medical device and to steer the medical device to the target treatment location. For example, navigation is an important tool in many electrophysiological (EP) procedures because it helps the user understand the placement of the medical device within the cardiac space. Additionally, navigation is often used to place medical devices at areas targeted for thermal treatment and/or ablation.
When the medical device is a focal catheter, for instance, the ablating surface may be directly imaged on the navigation system and there is a close, direct coupling between the navigation and the delivered therapy. However, other medical devices, such as balloon catheters, may have more complex geometry, and navigation electrodes on the device may not exactly correlate with the ablating surface (e.g., the surface of the balloon). Additionally, placement of these complex-geometry devices may be difficult to infer from fluoroscopic imaging or navigation systems relative to the targeted tissue regions.
Ablation of the tissue surrounding one or more pulmonary veins, such as the pulmonary vein ostium, has shown positive results in the treatment of certain types of atrial fibrillation. The success of this treatment, however, largely depends on occlusion of the pulmonary vein with the medical device, which may be difficult to determine using current imaging and navigation techniques, and delivery of the optimal treatment dose, which may depend on tissue thickness at the treatment site, another complicating factor. Additionally, pre-procedural identification of the ablation target sites and subsequent ablation tool selection (e.g., balloon catheter size) can facilitate faster and more predictable procedures prior to invasive interaction with the patient.